Right ventricular long-axis response to different chronic loading conditions: its relevance to clinical symptoms

The intervention timing in atrial septal defect (ASD) or pulmonary valvular stenosis (PVS) is more dependent on symptoms than right ventricular (RV) damage in clinical practice. RV long-axis function is sensitive in revealing RV myocardial dysfunction. We evaluate the impact of different chronic loading conditions on RV long-axis function and its relationship to patients' symptoms in ASD or PVS.

Transthoracic echocardiography was performed in normals (n=39) and patients with isolated secundum ASD (n=45) or PVS (n=38). RV volume- and pressure-overloading were defined as the ratio of RV/left ventricular end-diastolic dimension ≥ 0.5 and RV systolic pressure ≥ 40 mmHg, respectively. RV long-axis dysfunction was defined as M-mode tricuspid annular plane systolic excursion (TAPSE) <1.6 cm. New York Heart Association (NYHA) functional class and other symptoms (decreased exercise tolerance, palpitation and chest pain) were recorded.

Thirty-nine (32.0%) had normal loading (Group 1; 39 normals); 24 (19.6%) had isolated volume-overloading (Group 2; all ASDs); 21 (17.2%) had isolated pressure-overloading (Group 3; 21 PVSs) and 38 (31.1%) had both overloading conditions (Group 4; 21 ASDs and 17 PVSs). RV long-axis dysfunction in abnormal loading groups were zero (0%, Group 2), 21 (100%, Group 3) and 22 (57.8%, Group 4) (χ(2)=45.9, p<0.001). Group 3 were more symptomatic (NYHA functional class 2.5 ± 0.6 versus 1.6 ± 0.5, p<0.05) and had lower TAPSE (1.6 ± 0.4 versus 3.0 ± 0.7 cm, p<0.05) than Group 2. RV long-axis dysfunction was the strongest predictor of the presence of symptoms (odds ratio=9.298, p<0.001).

Chronic volume-overloading accentuates while pressure-overloading attenuates RV long-axis excursion and its impairment was associated with the presence of symptoms.